with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a complex peak
structure with a duration of about 30 sec. The peak count rate
was ~1100 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 04:25:53.1 UT, 132.2 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source located at RA, Dec 120.25774, 7.66265 which
is equivalent to:

RA(J2000) = 08h 01m 01.86s
Dec(J2000) = +07d 39' 45.5"

with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 70 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 2.92
x 10^20 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 135 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at

with a 90%-confidence error radius of about 0.64 arc sec. This position is 4.4
arc sec. from the center of the XRT error circle. The estimated magnitude is
19.15 with a 1-sigma error of about 0.15. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.02.
Burst Advocate for this burst is P. D'Avanzo (paolo.davanzo AT brera.inaf.it).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)

GCN Circular #19317
WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report
on behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, responded to Swift GRB 160417A (D'Avanzo et al.,
GCN 19316) about 10 minutes after the trigger. Observations were
performed with an automatic sequence in the clear (roughly R), V,
and I filters, and the exposure time was 20 s per image.
Inside the XRT error circle we detected an un-cataloged
source with coordinates of :

RA = 08:01:01.64 (J2000)
DEC= +07:39:46.60 (J2000)

The object location is consistent with the position reported
from UVOT (D'Avanzo et al., GCN 19316). The object has clear band mag
of ~17.9 about 10 minutes after the burst.
Follow-up observations are encouraged.

with an uncertainty of 1.8 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the
Swift-XRT team.

If the light curve continues to decay with a power-law decay index of
0.59, the count rate at T+24 hours will be 0.013 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.9 x
10^-13 (4.3 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00683076.
This circular is an official product of the Swift-XRT team.

GCN Circular #19321
Veli-Pekka Hentunen, Markku Nissinen and Tuomo Salmi (Taurus Hill
Observatory, Varkaus, Finland) report:
We have detected GRB 160417A optical afterglow at iTelescope observatory
T11 (Mayhill, New Mexico) using 0.50-m f/6.8 astrograph and FLI
PL11002M CCD. The observations were started at 2016-04-17
05:08:31 (UT). Two unfiltered images with 300 sec exposure time were taken.
The afterglow was detected at the position RA 08:01:01.65 and DEC
+07:39:47.6.
The following magnitude was obtained from the observations using
USNO-B1.0 0976-0191477 (R2=16.67) as a comparison star:

GCN Circular #19322
A. A. Breeveld (UCL-MSSL) and P. D'Avanzo (INAF-OAB)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 160417A
136 s after the BAT trigger (D'Avanzo et al., GCN Circ. 19316).
The source reported for the UVOT in the initial GCN and also by Zheng=20
and Filippenko (GCN Circ. 19317) is found to be fading.
The preliminary UVOT position is:

with an uncertainty of 1.9 arcmin, (radius, sys+stat,
90% containment). The partial coding was 41%.
The mask-weighted light curve shows a multi-peak episode
starting ~T-4 sec, and ending around ~T+20 sec.
T90 (15-350 keV) is 15 +- 2 sec (estimated error including
systematics).
The time-averaged spectrum from T-2.14 to T+13.89 sec
is best fit by a simple power-law model. The power law index
of the time-averaged spectrum is 1.93 +- 0.24. The fluence
in the 15-150 keV band is 5.9 +- 0.8 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T+1.51 sec in the
15-150 keV band is 1.0 +- 0.3 ph/cm2/sec. All the quoted
errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/683076/BA/

GCN Circular #19324
J.-J. Zhang, J. Mao, and J.-M. Bai (YNAO) report:
We observed the field of GRB 160417A (D'Avanzo et al., GCN 19316) with the 2.4-meter optical telescope at Gao-Mei-Gu (GMG)
station of Yunnan Observatories. Observations began from 12:30:03 UT, Apr. 17th, 2016, about 8.2 hours after the trigger.
We obtained the following results at the afterglow position: r~21.1+/- 0.3 mag, i>20.9 mag, and g>21.8 mag.

GCN Circular #19384
V. V. Golovnia (Main Astro Obs., Kyiv)
report:
We have undertaken the review of the sky area of GRB 160417A (J.P. Osborne
et al. GCN Circ. 19318) on astronegatives, collected in Ukrainian plate
archive (1976-1996). All the plates with the possible object appearance are
digitized using Epson Expression 10000XL flatbed scanner and the images
have been placed into Golosiiv Plate Archive database DBGPA with open
access to them. The list of plates is given in the table: